With exhaust systems, it is known to introduce different liquid educts into the gas flow in order to trigger different reactions. For example, liquid fuel can be injected upstream of an oxidation catalytic converter in order to bring about heating-up of the exhaust gas flow through a subsequent, exothermal reaction in the catalytic converter and thereby indirectly heating-up of downstream exhaust gas treatment devices. For example, a particle filter for its regeneration can be heated up to a self-igniting temperature in this manner in order to burn off a soot charge. Likewise, a NOX storage catalytic converter can be brought up to its operating temperature through such a measure. Furthermore, it is possible, in principle, to introduce ammonia or urea or a watery urea solution in liquid form into the exhaust gas flow in order to convert nitric oxides in a downstream SCR catalytic converter.
With all these applications, it is of increased importance that the liquid educt injected in the exhaust gas evaporates as completely as possible before it reaches the respective exhaust gas treatment device in which it is required. For example, mixing devices, swirling devices and special evaporation devices as well as any combinations of such devices can be used for this purpose, which bring about extensive evaporation of the liquid and homogenization of the gas-vapor mixture. Devices of this type can however be accompanied with a comparatively high flow resistance which can have a disadvantageous effect on the efficiency of the internal combustion engine.
In addition, devices of this type can also be employed with other technologies. For example with a burner, a liquid fuel can be introduced into an air flow in order to create a corresponding combustion reaction in a combustion chamber of the burner. Burners of this type can be used for example with a fuel cell system or with gas turbine plants.